How Common Is Anaphylaxis Following Vaccination?

Forty-one percent of reports included patients without a history of hypersensitivity

Anaphylaxis following vaccination appears to be a rare event in the US, according to a study published in The Journal of Allergy and Clinical Immunology.

To investigate the incidence of anaphylaxis after vaccination, study authors reviewed data submitted to the Vaccine Adverse Event Reporting System (VAERS) between 1990 and 2016. “We reviewed all serious reports, and all non-serious reports with available medical records, to determine if they met the Brighton Collaboration case definition (BCCD) for anaphylaxis or were diagnosed by a physician,” the authors explained.

Among a total of 467,960 VAERS reports identified during the study period, 828 met the criteria for anaphylaxis (describing symptoms 1 day after receiving vaccine). The majority of cases were classified as serious (79%) and most had medical records available for review (81%).

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Results showed that for patients aged <19 years (N=478), 65% were male and childhood vaccines (combination measles, mumps, and rubella [MMR] vaccine [196 reports], varicella vaccines [178 reports], vaccines containing diphtheria toxoids, tetanus toxoids, and/or acellular pertussis [165 reports]) were most commonly reported. For patients aged ≥19 years (N=350), 80% were female and flu vaccines were most commonly reported (224 reports). Moreover, 41% of the reports included patients without a history of hypersensitivity; of the 8 deaths identified, half occurred in patients with no history of hypersensitivity.

Based on the findings, the authors concluded that “anaphylaxis of severe or life-threatening severity is very uncommon, but can even occur among persons without a history of hypersensitivity; vaccine providers should be prepared to respond immediately.”